Well drilling unit



Oct. 6, 1936. L W, KRALL 2,056,471

WELL DRILLING UNIT Filed May 2, 1953 III/11111,

Patented Oct. 6, 1936 PATENT OFFICE WELL DRILLIN G UNIT Leo W. Krall,

Houston, Tex.

Application May 2, 1933, Serial No. 668,908

1 Claim.

'I'he invention relates to an improvement in a well drilling unit andthe method of drilling a well with such unit, and comprises a unitarymechanism which may be lowered into the Well 5 bore as the drillingproceeds and which is made up of a motor, the drill bit to be driventhereby, a pump to circulate the iiushing liquid and a carrier for thesllt or cuttings from the bit.

It is one of the objects of the present invention to provide a singleunit which may be lowered into the well bore on a cable or suitableequipment to perform the drilling operation and in which the motivepower is furnished at a point adjacent the surface being drilled.

Another object of the invention is to provide a composite drilling unitwhich can be submerged in a column of liquid at least of a height equalto the length of the unit so that flushing liquid can be drawn in at thetop of the unit and discharged at the bottom to remove the cuttings fromthe drill bit.

It is another object of the invention to provide in combination with acomplete drilling unit a silt box to trap the cuttings from the bit sothat the drilling unit needonly be removed from the well when thesilt-box has accumulated a full charge of cuttings from the bit.

Another object of my invention is to provide a drilling unit wherein thedrill bit and the pump for circulating liquid to the bit are bothoperated by the same power unit.

Still another object of the invention is to provide a drilling unit tobe lowered into the well bore so that a circulation of flushing liquidmay be maintained' against the force of the bit by a pump which is madeup as a part of the drilling unit.

It is one of the objects of the invention to perform the drillingoperation by the rotary method of drilling without filling the Well borefull of flushing fluid in order to maintain the circulation thereof, butto only provide a suflicient column of flushing liquid in the Well tosubmerge the drilling unit or to provide the desired hydrostaticpressure upon the formation being drilled.

Other and further objects of the invention will be readily apparent whenthe following description is considered in connection with theaccompanying drawing wherein:

Fig. 1 is a central, vertical, sectional view of the drilling unitdisposed in the well bore in drilling position and showing certain ofthe parts in section.

Fig. 2 is a section taken on the line 2-2 of Fig. 1, and showing therelation of the anchor plates to their supporting housing. l

Fig. 3 is a diagrammatic view illustrating the manner of using theinvention.

In the drilling of wells by the rotary method it is the usual practiceto accomplish the rotation of the drill bit in the bottom of the wellbore by (Cl. Z55-4) means of the drill stem and the rotary table drivenfrom the surface. This, oi.' course, entails an enormous expenditure forequipment and the inconvenience and hazard of constantly rotating thedrill stem in order to drill the well. With my in- 6 vention, Icontemplate a composite drilling unit which can be lowered into the wellon a cable or otherwise and which will so anchor itself in position thatall of the functions necessary to perform the drilling operation will becompleted at the 10 bottom of the well. In other words, the completedrill stem and the slush pumps now used on the surface as well as therotary equipment can be dispensed with. In vaddition to these enormoussimplifications in the equipment, it is also pos- 15 sible to drill thewell with but a small head or column of flushing liquid in the well.This is also of material advantage because in many instances thepressure of the column of heavy mud iilling the well bore causes such anenormous pressure 20 upon the formation being drilled that productivesands are often mudded off and passedby during the drilling operation.It will also be seen that the guiding action of the shoes restrains thebit to the limit, thus making a straight hole possible. 25

Fig. 3 illustrates generally the apparatus used in practicing thepresent invention. The well bore is indicated at 2. Disposed in the wellbore is the composite drilling unit indicated at 3. This unit is adaptedto be raised and lowered from the 30 well by means of the cable or othersuitable support 4 which is shown as passing over the derrick 5 andcontrolled as to movement by the draw works or reel 6.

I'he drilling unit 3 is shown as carrying the 35 drill 'l which rotateson the surface 8 which is being cut.

The drilling unit 3 embodies a motor I0 which is disposed within thehousing Il. The motor I0 imparts rotation to the shaft l2 which drives40 the reduction gears I3 mounted ln the housing II. These reductiongears tend to rotate what will be known as the drill shaft I4 in orderto rotate the drill 1. It is to be understood that the motor I0 may beof any suitable design, and has connected thereto the conduit or cablei6 which may extend to the surface as a separate unit or be incorporatedwithin the cable 4 as seen at the top of Fig. 1.

It seems obvious that upon rotation of the motor I0, the drill l will becaused to rotate. It is, of course, necessary to wash the cuttings andsilt away from the surface 8 in order to facilitate the drillingoperation. To accomplish this, the circulating pump 20 has beenincorporated 'as a part of the unit and this pump is disposed in thehousing 2| which is shown as connected to the housing Il of the motor.'I'he pump includes the impeller 22 which is of the centrifugal type anddischarges the liquid into the housing 2l where so it enters Atheope'ings 23 in the shaft I2, which is of hollow construction. It is tobe understood that the shaft I2 of the motor extends above the housingIl in order to have the impeller 22 connected therewith.

The supply of liquid for`the pump 20 is received through the perforatedinlet pipe 25 which extends upwardly from` the housing 2l. 'I'his pipeextends into the silt box or cutting accumulator l0 and it is from thissilt box 30 that the liquid is drawn by the pump 2li.

The silt box includes the tubular housing 3| which may be ofconsiderable le` ligth as seen in Fig. 3, in order to receive a goodlysupply of cuttings from the drill bit. It seems obvious that if theliquid is discharged at the bit 'i that it will be forced to passupwardly around the housing Il and up around the silt box 2 until itreaches' the openings 32. The suction in the upper-end" of the pipe 25,as at 33, will, ofcourse, aid in the circulation of the liquid.

Disposed within the cylinder 2l is a diaphragm 34 which serves as asupport and a receiver for the silt. This diaphragm'may be provided witha suitable screen 35 and has openings Il therein so that there will be adrainage of the liquid from the accumulating silt. To facilitate thisdrainage small openings l1 are provided in the stem 2l below thediaphragm s0 that there will be a suction created within the chamber 38which is formed'by the base plate 89 and the diaphragm.

A piston 40 is shown as nxed on the stern 26 and is provided with anupwardly opening valve 4I and a downwardly opening valve 42. Thesevalves control the flow of a suitable pressure-liquid within the chamberIl formed in the base of the cylinder Il. These valves are normally heldclosed by a spring such as Il, and are only caused to open when apredetermined pressure is exerted. It will be noted that the connectionof the cylinder 3i with the stem 25 is a sliding connection which issealed by the stumng box u. The springs 44 may be so adjusted that whenthe drilling unit is suspended by the cable 4 the drill blt, the motor,and the stem 25 will only slightly be permitted to move downward as thedrilling proceeds without movement of the silt box 3|. In this mannerthe weight to be disposed upon the drill 1 can be accurately measured bysuitable gauges on the ground surface. When it is desired to raise theunit an upward pull on the cable 4 will, of course, cause the piston tomove to the base of the cylinder and the weight of the drilling unit canthen be lifted. On the other hand, if weight in addition to that of thepump anchor plates and silt barrel is needed. additional weight can beadded to top of the silt barrel.

In order that the drilling unit may resist the tendency to rotate whenpower is applied to the drill, the anchor plates 50 have been provided.These may be grooved to facilitate gripping action. These plates may bearranged in any desired number. three having been shown in the presentillustration. These plates are shown as connected to the drilling imitby means of the links such as 5I and l2 adjacent the top and by thelinks 53 adjacent the base. These links may be attached either to thesilt box or to the motor housing and are so arranged that the housingand silt box may be in limit independent in movement with respect to thetraction plates or the traction plates may move relative to the motor.It is intended that these traction plates may be of any desired lengthin order to present a sumvcient surface 54' which will engage with thewall 5l of the well bore and create a frictional or gripping resistanceto prevent rotation of the drillingr unit. It is contemplated that thegravitational force of these anchor plates against the formation wallwill be sufficient to prevent rotation of the drilling unit.

vIn order that all of the plates 50 will be retained at the sameelevation a guide ring 5l is "ity will pull the plates lll downwardly sothat they will pivot outwardly and engage the wall of the well. As themotor rotates, the drill will be caused to rotate and flushing liquidwill be discharged from the drill. The flushing liquid carrying thecuttings and silt will iiow upwardly around the silt box 3i and be drawninto the openings l2 so that there is a complete circulation through thedrilling unit. It seems obvious if desired only a sui'iicient column ofliquid need be maintained in the well to submerge the drilling unit. Inother words only a slight hydraulic pressure will be caused on theformation being drilled by thevcolumn of liquid. 'Ihe line 8l of Fig. 3indicates the elevation to which the column of liquid may be maintained.It is contemplated, of course, that the well bore may be completelynlled with liquid if desired. Such a practice is sometimes necessarywhen heavy pressures are encountered during the operation. It is, ofcourse, possible, however, to use only a short column of liquid andclose the head of the well by a suitable casing head or blowoutpreventer, such as Il In order to determine whether or not there is asufficient column of liquid in the well, a contact disc 82 has beenprovided' in the top of the silt box 3|. This disc may be pliable, andwhen a sufficient pressure of liquid is exerted on this disc it willmove downwardly to make the contact with the point which is grounded tothe disc as indicated at il. This contact may be indicated to thedriller on the surface by any suitable signal.

When there is an insufllcient head of drilling fluid, the diaphragm B2may raise away from the contact I3 and indicate this fact to thedriller.

While one form of the invention has been shown, it is understood that itmay be varied to suit the conditions encountered. The principal novelfeature is the provision of a complete drilling unit to be lowered intothe well bore to perform the drilling operation while utilizing only ashort column of liquid -in the well bore. It is to be understood, ofcourse, that a casing may be inserted into the well bore as it isdrilled to prevent caving when the formation so requires.

What is claimed is:

In a well drilling unit a motor, a shaft rotatable thereby, acirculating pump on said shaft, openings through said shaft for thedischarge from said pump, a drill bit adapted to receive said dischargeas a flushing fluid, and anchor plates pivoted to` settle by gravityagainst the wall of the well bore to resist rotation of said unit.

LEOW.KRALL.

